The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingDisposal
Hint:
When scrapping a vehicle equipped with an srs or disposing
of the front passenger side knee airbag, be sure to deploy the
airbag first in accordance with the procedure described
below. If any abnormality occurs with the airbag deployment,
contact the service dept. Of toyota motor sales,
...
Starter relay
On-vehicle inspection
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove starter relay
Remove the starter relay fr ...
If the engine will not start
If the engine will not start
even though correct starting
procedures are being
followed, consider
each of the following
points:
The engine will not start
even though the starter
motor operates normally
One of the following may be the
cause of the problem:
There may not be sufficient
fuel in the v ...